The present invention relates generally to an instrument panel used in a vehicle having an inflatable cushion or airbag module, and more particularly to an instrument panel cover having an integral hidden door and the method of manufacture thereof. The present invention also relates to the materials used for the instrument panels and methods of employing the same.
Vehicles are now equipped with some type of inflatable cushions or airbag modules and other vehicle components have been modified to accommodate the use of such systems. For example, most passenger side airbag modules are disposed within and behind an instrument panel which extends across at least a portion of the width of a vehicle compartment. During assembly and/or manufacture, an instrument panel in a vehicle having a passenger side airbag module requires a discrete door or predetermined area which will open during initiation of the airbag so that the inflatable cushion can deploy through an opening in the instrument panel or dashboard. This door is designed to open in response to the force of the expanding inflatable cushion. In other words as the pressure in the inflatable cushion increases, the volume of the cushion increases and applies a force to a portion of the door wherein the door selectively separates from the remaining portion of the instrument panel to permit the inflatable cushion to deploy therethrough.
In some applications, the instrument panel was formed with an opening adjacent to the location of the airbag module. Then opening was covered by a separate door which is secured to the instrument panel and faces the occupants of the vehicle. However, the outer periphery of such a door is clearly visible to the vehicle occupant and may create an unpleasing appearance to the instrument panel.
Therefore it is desirable to provide a hidden passenger airbag door in lieu of a separate door/airbag system assembly for aesthetic reasons. In order to provide this hidden airbag door (e.g., no tear seams are visible from the exterior show surface of the instrument panel or dashboard) a tear seam must be provided in the materials of the instrument panel wherein the tear seam allows for deployment of the inflatable cushion during an activation event while being invisible to the naked eye.
In one application, a CO2 laser is used to penetrate or score partially through some or all of the components of the instrument panel in order to provide the “tear seam”. A score depth consistency is highly dependent on the ability of the skin laser to absorb the laser light in a consistent fashion along the entire length of the tear seam. Score depth consistency at the desired penetration depth is required to achieve a desired “breakthrough force” to ensure proper airbag deployment as well as provide an adequate resistive force to external loads applied to the door from the A-side or show surface of the skin layer during normal vehicle operation. Visual readthrough of the seam on the top side or show surface of the skin layer is undesirable and highly dependent upon the intensity of the power required of the laser to “burn through” the retainer substrate and foam layers in addition to the absorption.
Consistent absorption of laser light in the skin layer of the tri-laminate construction can be difficult, particularly with an olefin based skin (compact sheet). Readthrough of the laser-scored seam can also be an issue and is highly dependent on the materials of construction.
Due to ongoing desires for improving the aesthetics of the passenger compartment, it is desirable to provide aesthetically pleasing, functional alternatives to the conventional instrument panels having a separate door covering the airbag module.